ieee-754 to decimal conversion

You have asked the same question before. Apparently no forum member has a ready to use solution or is motivated to share it (if so, they probably have respectable reasons). Personally, I'm not involved with float math up to now.

You also got valuable links by batfink. Additionally, I like to refer to synthesizable float packages, that should basically contain the means needed to handle your project. http://www.vhdl.org/vhdl-200x/vhdl-200x-ft/packages/files.html

P.S.: As another remark, I don't think that you specified your intentions completely. decimal doesn't designate a particular number format to my opinion. If you intend e.g. a printable number representation, you should tell in detail. There are many options as true integer, fixed or variable decimal point, that affect the design.